1. Field of the Invention
The present invention relates to seams for industrial fabrics, such as papermakers fabrics and a seaming method.
2. Description of Related Art
When used on papermaking equipment, papermakers fabrics are configured as endless belts to form and/or transport a paper product as it is made. Woven papermakers fabrics are made by either conventional flat or endless weaving. With flat woven fabrics, the warp yarns are oriented in the machine direction of the papermaking equipment on which the fabric is used. With endless woven fabrics, the weft yarns are oriented in the machine direction during usage.
Endless weaving techniques may be used to weave a seamless papermakers fabrics. However, there are practical limitations on the overall size of endless woven fabrics as well as inherent installation difficulties. Moreover, not all papermaking equipment is designed to accept the installation of an endless woven seamless fabric. Consequently, both endless and flat woven papermakers fabrics are often supplied having opposing ends which are joined during installation of the fabric on papermaking equipment.
A variety of seaming techniques are well known in the art. One conventional method of seaming is to form alternating machine direction yarns on each end of the fabric into a series of loops. The loops of the respective fabric ends are then intermeshed during fabric installation to define a channel through which a pintle is inserted to lock the ends together.
For example, U.S. Pat. Nos. 4,206,331; 4,438,789; 4,469,142; 4,846,231; 4,824,525; and 4,883,096 disclose a variety of pin seams wherein the machine direction yarns are utilized to form the end loops. In each of those patents, individual machine direction yarns are woven back into the fabric to form a series of single loops. However, the loops of such seams are prone to stretching and fraying which may compromise the strength of the endless belt. The seam is typically the weak point of the installed fabric and may fail after repeated usage on modern high speed papermaking equipment.
It would be desirable to provide a papermakers fabric with reinforced machine direction seaming loops with increased structural stability. It would also be desirable to have a fabric with reinforced seaming loops without significantly increasing the bulk or thickness of the fabric at the seam.